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Walsh MP, Phelps JM, Lennon ME, Yufit DS, Kitching MO. Enantioselective synthesis of ammonium cations. Nature 2021; 597:70-76. [PMID: 34471272 DOI: 10.1038/s41586-021-03735-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 06/17/2021] [Indexed: 02/07/2023]
Abstract
Control of molecular chirality is a fundamental challenge in organic synthesis. Whereas methods to construct carbon stereocentres enantioselectively are well established, routes to synthesize enriched heteroatomic stereocentres have garnered less attention1-5. Of those atoms commonly present in organic molecules, nitrogen is the most difficult to control stereochemically. Although a limited number of resolution processes have been demonstrated6-8, no general methodology exists to enantioselectively prepare a nitrogen stereocentre. Here we show that control of the chirality of ammonium cations is easily achieved through a supramolecular recognition process. By combining enantioselective ammonium recognition mediated by 1,1'-bi-2-naphthol scaffolds with conditions that allow the nitrogen stereocentre to racemize, chiral ammonium cations can be produced in excellent yields and selectivities. Mechanistic investigations demonstrate that, through a combination of solution and solid-phase recognition, a thermodynamically driven adductive crystallization process is responsible for the observed selectivity. Distinct from processes based on dynamic and kinetic resolution, which are under kinetic control, this allows for increased selectivity over time by a self-corrective process. The importance of nitrogen stereocentres can be revealed through a stereoselective supramolecular recognition, which is not possible with naturally occurring pseudoenantiomeric Cinchona alkaloids. With practical access to the enantiomeric forms of ammonium cations, this previously ignored stereocentre is now available to be explored.
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Affiliation(s)
- Mark P Walsh
- Department of Chemistry, Durham University, Durham, UK
| | | | - Marc E Lennon
- Department of Chemistry, Durham University, Durham, UK
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5
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Ishiwari F, Takeuchi N, Sato T, Yamazaki H, Osuga R, Kondo JN, Fukushima T. Rigid-to-Flexible Conformational Transformation: An Efficient Route to Ring-Opening of a Tröger's Base-Containing Ladder Polymer. ACS Macro Lett 2017; 6:775-780. [PMID: 35650861 DOI: 10.1021/acsmacrolett.7b00385] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis of ladder polymers is still a big challenge in polymer chemistry, and in particular, there are few examples of conformationally flexible well-defined ladder polymers. Here we report an efficient and convenient route to conformationally flexible ladder polymers, which is based on a postpolymerization reaction of a rigid ladder polymer containing Tröger's base in its main chain. The postpolymerization reaction involves sequential N-methylation and hydrolysis for the Tröger's base unit, resulting in a diazacyclooctane skeleton that can exhibit a ring-flipping motion. Molecular dynamics simulations predicted that this motion provides conformational flexibility with the resultant ladder polymer, which was demonstrated by 1H NMR spectroscopy in solution. The presence of the diazacyclooctane units in the flexible ladder polymer allowed further functionalization through reactions involving its secondary amine moiety. The present synthetic method may lead to the development of a new class of ladder polymers that exhibit both conformational and design flexibility.
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Affiliation(s)
- Fumitaka Ishiwari
- Laboratory for Chemistry
and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku,
Yokohama 226-8503, Japan
| | - Nobuhiko Takeuchi
- Laboratory for Chemistry
and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku,
Yokohama 226-8503, Japan
| | - Takahiro Sato
- Laboratory for Chemistry
and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku,
Yokohama 226-8503, Japan
| | - Hiroshi Yamazaki
- Laboratory for Chemistry
and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku,
Yokohama 226-8503, Japan
| | - Ryota Osuga
- Laboratory for Chemistry
and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku,
Yokohama 226-8503, Japan
| | - Junko N. Kondo
- Laboratory for Chemistry
and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku,
Yokohama 226-8503, Japan
| | - Takanori Fukushima
- Laboratory for Chemistry
and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku,
Yokohama 226-8503, Japan
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10
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Artacho J, Ascic E, Rantanen T, Wallentin CJ, Dawaigher S, Bergquist KE, Harmata M, Snieckus V, Wärnmark K. Tröger’s Base Twisted Amides: Endo Functionalization and Synthesis of an Inverted Crown Ether. Org Lett 2012; 14:4706-9. [DOI: 10.1021/ol302022y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Josep Artacho
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, Department of Chemistry, University of Missouri—Columbia, Columbia, Missouri 65211, United States, and Snieckus Innovations and Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - Erhad Ascic
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, Department of Chemistry, University of Missouri—Columbia, Columbia, Missouri 65211, United States, and Snieckus Innovations and Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - Toni Rantanen
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, Department of Chemistry, University of Missouri—Columbia, Columbia, Missouri 65211, United States, and Snieckus Innovations and Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - Carl-Johan Wallentin
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, Department of Chemistry, University of Missouri—Columbia, Columbia, Missouri 65211, United States, and Snieckus Innovations and Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - Sami Dawaigher
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, Department of Chemistry, University of Missouri—Columbia, Columbia, Missouri 65211, United States, and Snieckus Innovations and Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - Karl-Erik Bergquist
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, Department of Chemistry, University of Missouri—Columbia, Columbia, Missouri 65211, United States, and Snieckus Innovations and Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - Michael Harmata
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, Department of Chemistry, University of Missouri—Columbia, Columbia, Missouri 65211, United States, and Snieckus Innovations and Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - Victor Snieckus
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, Department of Chemistry, University of Missouri—Columbia, Columbia, Missouri 65211, United States, and Snieckus Innovations and Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
| | - Kenneth Wärnmark
- Centre for Analysis and Synthesis, Department of Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden, Department of Chemistry, University of Missouri—Columbia, Columbia, Missouri 65211, United States, and Snieckus Innovations and Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada
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18
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Barry NPE, Austeri M, Lacour J, Therrien B. Highly Efficient NMR Enantiodiscrimination of Chiral Octanuclear Metalla-Boxes in Polar Solvent. Organometallics 2009. [DOI: 10.1021/om900461s] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Nicolas P. E. Barry
- Institut de Chimie, Université de Neuchâtel, Case postale 158, CH-2009 Neuchâtel, Switzerland
| | - Martina Austeri
- Department of Organic Chemistry, University of Geneva, Quai E. Ansermet 30, CH-1211, Geneva 4, Switzerland
| | - Jérôme Lacour
- Department of Organic Chemistry, University of Geneva, Quai E. Ansermet 30, CH-1211, Geneva 4, Switzerland
| | - Bruno Therrien
- Institut de Chimie, Université de Neuchâtel, Case postale 158, CH-2009 Neuchâtel, Switzerland
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